One known method used broadly for supplying a molecular beam source material is to evaporate an element semiconductor material. Recently, in contrast to that, new technology called gas source molecular beam epitaxy (GSMBE) was introduced, in which organic compound gases including component elements of semiconductor are supplied from the outside of the apparatus. FIG. 5 is a schematic diagram showing a construction of a conventional GSMBE apparatus.
In a crystal growth chamber 1, as well as a metal-source type effusion cell 5 for spouting an evaporated element source material, gas-source type gas cells 22A and 22B for spouting metal organic source gases are provided.
Moreover, in the crystal growth chamber 1, a substrate 2 on which crystal is to be grown, a substrate holder 3 for supporting the substrate 2, a liquid nitrogen shroud 6 for cooling the inner wall of the crystal growth chamber 1, and shutters for turning on or off molecular beams from each cell are also provided.
The crystal growth chamber 1 is connected to a gate valve 23 for use when the substrate 2 is replaced by another substrate located outside. A turbo molecular pump 12 is provied for evacuating the crystal growth chamber 1 to ultra high vacuum via gate valve 24. Furthermore, source gas bombs 33A and 33B are connected to the crystal growth chamber 1 via stop valves 31A, 31B, 34A, and 34B, and mass flow controller 32A and 32B. A member marked 4 is a manipulator for supporting the substrate 2, while an oil trap and rotary pump are denoted by 13 and 14, respectively.
In a GSMBE method, unlike a method which uses metal-source type effusion cells, supply of source materials can be carried out without opening a vacuum chamber. Thus, operation efficiency of the growth apparatus can be improved and the apparatus can be effectively used for mass production.